The warning was issued as a result of the fire at the Shepherd's Court tower block in west London last year, as experts believed that insulation panels installed as part of an earlier refurbishment may have helped facilitate the spread of the fire up the side of the building.

Meanwhile, campaign group Justice4Grenfell has said it will set up an unofficial database of the victims of the fire amid distrust of the official death toll from police.

Ishmahil Blagrove, a co-ordinator for the group, said: "There are people who are still missing, people who are undocumented, we are unhappy with the 79 victims who have been recorded by the media and the police.

"We want to do some probing to find out how accurate that figure is and give them something that reflects a fuller picture."

He said that Ramadan meant there were visitors in the tower at the time of the fire and "dozens" staying in flats who "shouldn't have been there".

'No stone unturned'

Earlier, an open letter from residents, part of the campaign, demanded their voices were "heard and fully included" in the inquiry into the blaze.

The group said bereaved families and survivors should be given funding for legal representation in that probe.

People who live at the Hurstway, Testerton, Barandon and Grenfell Walks on the Lancaster West estate said in the letter: "The investigation must leave no stone unturned.

"It must identify each and every individual and organisation who must bear responsibility and accountability for this tragedy and the mishandling of the aftermath.

"There must be swift recommendations to ensure there can be no chance of a repeat of this disaster elsewhere."

The blaze, believed to have started in a fridge-freezer, destroyed 151 homes in the north Kensington block and in the surrounding area of the London Borough of Kensington and Chelsea.

BBC home affairs correspondent Tom Symonds said: "The various regulations say you can use cladding that is potentially going to burn in a fire as long as the system, the design that you put it in as part of, is safe and that is a separate sort of test.

"The government is doing a test of the materials, so again that is a different approach and I think there is a growing feeling that the goalposts have been moved and councils don't really know what is safe now."

The prime minister's official spokesman said evidence suggested the use of the cladding goes back into at least the last decade.

He added that the exact nature of the cladding investigation had not yet been determined, but it could be a second phase of the public inquiry into the Grenfell fire.

The expert panel, chaired by former London Fire commissioner and former government chief fire and rescue adviser Sir Ken Knight, will be made up of building and fire safety experts and will meet this week.

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Media caption"I can't do that to her": Sabah Abdullah lost his wife in the Grenfell Tower fire

Communities Secretary Sajid Javid said all councils should send in samples of cladding from tall buildings and schools and hospitals may do the same if they have concerns.

About 31,600 NHS and private hospitals, hospices, care homes and other providers were told by England's health and social care regulator, the Care Quality Commission, on Tuesday to review their fire safety.

Fire safety is one of the issues it can take into account when it inspects premises. It then tells local fire authorities about any problems found.

Meanwhile, shadow education secretary Angela Rayner has said that student accommodation providers should be urged to conduct safety checks.

'Massive inconsistency'

But it was no "great surprise" samples had failed fire tests, director of the Centre for Window and Cladding Technology David Metcalfe said.

He said it was never "entirely clear" under the regulations whether or not the products used in cladding had to be of limited combustibility.

What a filler material consists of is not defined, he explained, and regulations do not say "specifically the cladding should be of limited combustibility".

"Timber isn't an insulation product, it's not a filler material, so there's nothing stopping you using timber on a high-rise building - but the government now are saying that all cladding should be of limited combustibility - there is a massive inconsistency there."

The government had a new "strict interpretation" of the rules, he said.